The objective of the proposed research is to synthesize compounds with varying C-13 substituents and functionalized C-18 substituents in the estradiol, testosterone, 19-nortestosterone, progesterone and 19 norprogesterone series. These derivatives may lead to useful agents for male and female fertility control. The C-13 groups will be introduced by 1,2-addition of organometallic reagents to C-13 ketones of ring D 13,17-secosteroids that have attached at the 14 beta position a (3'-pentynyl) group. Cyclization of the C-13 carbonium ion generated with formic acid with simultaneous triple bond participation will yield 20-formoxy-delta 17(20)-pregnenes through an intermediate C-20 vinyl carbonium ion. These intermediates can be converted to either pregnanes or 17-keto steroids. Stereospecific Claisen rearrangement processes on 17 alpha-hydroxy-delta 13(17a)-D-homo-steroids also will be used to prepare additional C-18 substituted steroids. These steroids will be broadly evaluated for hormonal and antihormonal activity, and antifertility activity with the goal of obtaining enhanced hormonal activity or an increased separation of hormonal activities.